Contamination by accidental needle sticks has recently generated a plethora of inventions in the syringe field. With the increased risk of exposure of medical personnel to AIDS contaminated needles, this concern has grown geometrically over the past few years. Some of the "safety" syringes designed to reduce the risk of accidental sticks are seen in U.S. Pat. Nos. 4,650,468; 4,747,830; and 4,752,290. Other designs purporting to reduce contamination risks undoubtedly are being tried and/or developed to meet this growing crisis.
The main drawback to all of the syringes currently available is the need for manual retraction of the plunger by the user in order to effect retraction of the needle into a safe position. Since medical personnel must often administer scores of injections in a given day, only one lapse of cencentration is all that is necessary to expose the user to the risk of a potentially deadly stick.